How popular is Adolf?

Adolf is a rare first name for men but a very popular surname for both adults and children (#28256 out of 150436, Top 19%). (2000 U.S. Census)

Adolf reached its highest rank of #930 in the U.S. in the 1910s, but is not found in the list currently. (Top 2000 Names, 2015)

Which version is better?

with its source form and related boy names. Prominent related forms of Adolf are Ad, Adolfo(#1184 a year ago), Adolph and Adolphe. Other forms, like Addolph, are uncommon. These forms of Adolf were at the peak of their popularity in the 1880s (adoption of 0.1%) and have become significantly less conventional since, with versions such as Adolph becoming less fashionable.